1. Field of the Invention
The present invention relates to a method which makes it possible to pull a photographic film out of a cartridge which accommodates said photographic film such that said film is shielded from light, and more specifically, a method for separating a photographic film from a spool which engages the photographic film.
2. Description of the Related Art
In the case of 135 type photographic film cartridges, which are the most widely used type of film cartridge, the main body of the cartridge is constructed from two caps and a cartridge cylinder formed by forming a thin metal plate into the shape of a cylinder. The cartridge is constructed such that a spool around which the photographic film is wound is accommodated inside the cartridge main body. Methods for assembling such a photographic film cartridge include a method in which assembly is performed in a dark room so that a spool, around which a photographic film has been wound, is enveloped by a cartridge main body, and a method in which a cartridge main body which has already been temporarily assembled is disassembled into respective portions in a photographic film loading area inside a dark room, and a spool around which the photographic film is wound is inserted into the cartridge main body, after which the cartridge main body is re-assembled.
Alternatively, a method may be used in which a cartridge main body containing a spool around which no film is wound is constructed in a light room, after which a tongue-shaped guide plate is inserted into a film passage formed in the cartridge main body. A photographic film is inserted into the cartridge main body from the trailing end portion of the film by using the guide plate, and the trailing end portion of said photographic film is engaged with the spool. Thereafter, the photographic film is taken up into the cartridge main body by rotating the spool.
In accordance with the specification of U.S. Pat. Nos. 4,834,306 and the specification of 4,846,418, photographic film cartridges in which the cartridge main body is assembled from a molded resin, and which function so as to feed photographic film to the outside of the cartridge by the rotation of a spool, are disclosed. Such photographic film cartridges differ from their predecessors in that no photographic film leader portion protrudes from the cartridge main body regardless of whether the photographic film is unused or has been used. As a result, the following advantages are obtained: not only is the photographic film accommodated so that it is shielded from light, but handling of the film following use thereof is also simplified.
However, in the case of photographic film cartridges which have a photographic film feed-out function using the rotation of a spool, there is an increase in the number of constituent parts of the cartridge main body due to the fact that, for example, such cartridges are constructed so that the film passage formed in the cartridge main body can be opened or closed by means of a light-blocking cover, or due to the incorporation into the cartridge main body of a display member which indicates whether the film has been used or not or due to the use of a structure such as that disclosed in the specification of U.S. Pat. No. 5,049,912 may be used. Accordingly, it is difficult to increase the production efficiency in the case of methods in which the cartridge main body is disassembled and reassembled in a dark room in order to load the photographic film into the cartridge.
Further, even if such assembly work is automated, there are drawbacks problems in terms of workability when response to the occurrence of trouble is taken into consideration.
Moreover, at the time of development, photographic film which has already been used to take photographs is pulled out of the cartridge. However, since the trailing end portion of the photographic film is engaged with the spool, the film cannot be separated from the cartridge main body merely by pulling the film out. In the past, therefore, it has been the practice to cut the photographic film so that a portion of the film is left in the cartridge main body. However, in cases in which the photographic film remains in the cartridge main body, the cartridge main body cannot be reused "as it is". Further, in cases in which the resin material of the cartridge main body is melted and recycled as a raw material, the quality of the resin material drops if photographic film is mixed with the resin material. Accordingly, it is necessary to temporarily disassemble the cartridge main body and remove the photographic film fragments remaining therein. Thus, after-treatment of the cartridge main body is inconvenient.
As a means of solving the above-mentioned drawbacks and problems, the applicant of the present application has proposed a photographic film cartridge and a method for pulling a photographic film out of the cartridge, as disclosed in Japanese Patent Application Laid-Open No. 4-122925 and Japanese Patent Application Laid-Open No. 4-177251.
Specifically, in the photographic film cartridge disclosed in Japanese Patent Application Laid-Open No. 4-122925, a rod which can move a pawl is inserted into an insertion hole therefor which is exposed at the exterior of the cartridge main body, and the engagement between engagement pawls and engagement holes formed in the photographic film is released, after which the photographic film is pulled out of the cartridge.
However, in the structure disclosed in Japanese Patent Application Laid-Open No. 4-122925, it is necessary to form an insertion hole in the cartridge main body and provide a driving mechanism for the pawl movable rod. Accordingly, not only the structure of the cartridge main body but also the structure used to pull the film out becomes complicated.
Further, in the method for pulling a film out of a cartridge disclosed in Japanese Patent Application Laid-Open No. 4-177251, a rectangular hole is formed in a portion of the cartridge main body. When the photographic film is to be pulled out, a guide member is inserted from the rectangular hole, and the engagement between the photographic film and an engagement member is released. Moreover, the rectangular hole is ordinarily covered by a seal so that the interior of the cartridge main body is shielded from light. When the photographic film is pulled out, the seal is broken by the guide member. Further, the guide member is driven by an air cylinder provided in the cartridge case.
In this structure, a rectangular hole must be formed in the cartridge main body, and this hole must be covered by a seal. Accordingly, the structure of the cartridge main body becomes complicated. In addition, since an air cylinder is provided in the cartridge case, the structure for pulling out the film also becomes more complicated.
Further, there is also a structure in which a circular-arc-shaped separating member is inserted from the passage through which the photographic film is pulled out, and the engagement between the photographic film and engagement pawls is canceled by means of the separating member. In this structure, there is the concern need to form a rectangular hole or an insertion hole in the cartridge main body, and accordingly, the structure is simplified. However, there is the concern that the photographic film will be damaged by the separating member.